The present invention relates to an information recording medium such as a DVD (Digital Video Disk)-RAM (Random Access Memory) for recording predetermined information.
The present invention also relates to an information recording method for recording information on an information recording medium such as a DVD-RAM for recording predetermined information.
The present invention further relates to an information playback method for playing back information recorded on an information recording medium such as a DVD-RAM for recording predetermined information.
In recent years, systems for playing back the contents of optical discs that record video data (moving pictures), audio data, and the like have been developed, and have prevailed for the purpose of playing back movie software titles, karaoke data, and the like as in LDs (laser discs), video CDs (video compact discs), and the like. Information about recording contents such as titles is generally printed on the surfaces of such optical discs. Further, information about recording contents such as titles is generally added to the packages of these optical discs. This allows the user to obtain the recording contents of an optical disc without playing back the optical disc.
DVD standards that use MPEG2 (moving picture expert group) international standards, and also use an audio compression scheme such as AC-3 (digital audio compression), or the like, have been proposed. The DVD standards include read-only DVD video (or DVD-ROM), write-once DVD-R, and recordable/readable DVD-RW (or DVD-RAM).
The DVD video (DVD-ROM) standards support MPEG2 as a moving picture compression scheme, and AC-3 audio and MPEG audio in addition to linear PCM as audio recording schemes in accordance with the MPEG2 system layer. Furthermore, the DVD video standards are configured by adding sub-picture data obtained by runlength-compressing bitmap data for superimposed dialogs, and presentation control data (navigation data) for fast forward, rewind, data search, and the like. The standards also support the UDF Bridge format (a hybrid of UDF and ISO9660) to allow computers to read data.
An optical disc currently used in DVD video (DVD-ROM) is a single-sided, single-layered 12 cm disc having a storage amount around 4.7 GB (gigabytes). A single-sided, two-layered disc has a storage amount around 9.5 GB, and a double-sided, two-layered disc is capable of recording a large amount of data around 18 GB (when a laser of a wavelength of 650 nm is used for reading).
An optical disc currently used in DVD-RW (DVD-RAM) is a 12 cm disc, and has a storage amount of 2.6 GB (gigabytes) on one surface, i.e., 5.2 GB on the two surfaces. The currently available DVD-RAM optical disc has a smaller storage amount than that of a DVD-ROM disc of the corresponding size. However, technical developments for expanding the amount of the DVD-RAM disc have been extensively made, and it is certain that a DVD-RAM disc having a storage amount more than 4.7 GB on one surface will be available in the near future.
However, since an MPEG2 video file that can obtain high picture quality has a large data size, the currently available DVD-RAM disc (single-sided 2.6 GB disc or double-sided 5.2 GB disc) does not always have a sufficient recordable time (around 1 hour for 2.6 GB disc, around 2 hours for 5.2 GB disc).
Since the user can freely record data on the DVD-RAM disc, no information representing recording contents is generally printed on the disc surface. For the same reason, no information representing recording contents is generally printed on the package of the DVD-RAM disc.
To obtain the recording contents of the DVD-RAM disc at a glance at the disc appearance, the user must perform the following process. For example, the user grasps recording contents recorded on the DVD-RAM disc. The user creates information representing the recording contents of the DVD-RAM disc. The user writes the information representing the recording contents of the DVD-RAM disc on the disc surface. Alternatively, the user may add information representing the recording contents of the DVD-RAM disc to the disc package.
Since no information about recording contents is printed on the DVD-RAM disc, as described above, the user cannot obtain the recording contents of the optical disc at a glance at the disc appearance.
To obtain the recording contents of the optical disc at a glance at the appearance of the DVD-RAM disc, the user must perform predetermined processing for the disc.